1. Field of the Invention
This invention generally relates to laser-applied medical apparatuses, and in particular, to an apparatus for treating athlete's foot using a laser beam having a controlled energy level.
2. Background of the Invention
It has been proposed to treat athlete's foot with the irradiation of a laser beam having a predetermined energy level for a predetermined time period to the above-related U.S. counterpart of area of a person's skin affected by dermatophytosis as disclosed in the Japanese Patent Application, No. 58-239563, the foreign priority document of said related application, which has been assigned to the assignee of this application and is hereby incorporated by reference. The method of treatment of athlete's foot using a laser beam disclosed in the above-identified application is based on the fact that ringworms only live in the epidermis or the surface layer of the skin, and more specifically in the stratum corneum or stratum corneum layer, which is the outermost layer of the epidermis. Heat-sensitive nerves extend up to the corium or the true skin and they do not extend into the stratum corneum layer. If irradiation of a laser beam having an energy density of a predetermined amount or more is momentarily carried out to the affected part of skin for a predetermined time, the stratum corneum layer can be heated to a temperature suitable for the treatment of athlete's foot, e.g., 70.degree. C. or more, while maintaining the temperature of the true skin where heat-sensitive nerves exist, not causing any burn to the true skin.
Described more in detail, as long as an irradiation of a laser beam is such that the laser beam has an appropriate magnitude of energy density and is momentary and limited to a predetermined time duration or less, even if the stratum corneum layer is heated to a temperature effective to kill the ringworms living therein, the heat thus produced in the stratum corneum layer is effectively dissipated through the skin so that the temperature substantially drops to a low level by the time in which the heat reaches the heat-sensitive nerves in the true skin thereby preventing the patient from feeling heat. Accordingly, in order to relieve the patient from feeling heat during treatment, it is necessary that heating due to irradiation of the laser beam take place only at the surface of the epidermis, or more preferably within the stratum corneum layer, and not in the true skin. With such heating, an excellent treatment of athlete's foot can be carried out without causing the patient to feel heat.
Under the circumstances, in accordance with the above-identified application, it has been proposed to treat athlete's foot by the application of one or more irradiations of a laser beam having an energy density of 2 Joules/cm.sup.2 or more in a time period of 10 milliseconds or less to a part of the body affected by dermatophytosis. The treatment of athlete's foot with a laser beam would not require significant endurance of heat by the patient.
It is to be noted, however, that it is not only the foot of a body which can be affected by dermatophytosis, but also other parts of the body, such as hands, are also liable to be infected. Moreover, when the roots of fingers or toes are infected, the application of a laser beam having a predetermined energy level to such parts of a body is extremely difficult. Thus, a need exists for an apparatus which can apply a controlled laser beam to any part of a body freely without restrictions, thereby completely curing that part of the body which is affected by dermatophytosis. In addition, since a laser unit is inherently a high-power device, it is desirous that some kind of a safety feature be provided to terminate the treatment operation if the apparatus malfunctions for some reason.